Method and device for measuring physiological parameters at the wrist

ABSTRACT

A wrist-mounted device for measuring at least one physiological parameter of the user. The present invention enables such a measurement to preferably be transformed into clinically useful information about the user. Such information may then optionally be sent to medical personnel, for example at a contact and/or monitoring center, through a gateway device. The gateway device preferably communicates with the wrist-mounted device of the present invention through a wireless communication channel.

FIELD OF THE INVENTION

[0001] The present invention is of a method and device for measuring atleast one physiological parameter of a subject at the wrist, preferablyfor extracting clinically useful information thereof. More specifically,the present invention is of a device which may be worn at the wrist ofthe subject with a strap or other fastening article, and which may thenbe used to monitor the subject through measurement of the physiologicalparameter.

BACKGROUND OF THE INVENTION

[0002] Currently, a number of different types of devices are availablefor monitoring human subjects in a non-invasive manner. For example,heart function can be monitored in a patient through the use ofelectrodes which must be attached to the skin of the patient. Althoughnon-invasive, such equipment is nevertheless uncomfortable for thepatient, who is attached to a network of cables and wired sensors. Inaddition, such equipment is very expensive, limiting its use tohospitals and other medical settings in which both the cost and thediscomfort of the patient can be justified. Furthermore, patients maybecome anxious when examined by medical personnel, thereby significantlyaltering the normal readings for these patients.

[0003] However, there are many different situations in whichnon-invasive monitoring of a human subject is desired. For example, suchmonitoring could be very useful as part of the overall healthmaintenance of the human subject, and could be used in order to detect adeterioration in the physiological condition of the subject before aconcomitant deterioration in the health of the subject becomesnoticeable. Examples of adverse physiological conditions which could bedetected with regular non-invasive monitoring include but are notlimited to excessive weight gain or less; arrhythmia and other heartconditions; incipient diabetes in the form of improper glucosemetabolism; and loss of lung capacity or other problems withrespiration.

[0004] Heart rate and blood pressure are important factors indetermining the state of a person's health and the physical condition ofa person's body in response to physical or emotional stress. Periodicmonitoring of these physical parameters is particularly important forindividuals having cardiac disease and/or lowered cardiac functioning,or high blood pressure. However, physically healthy individuals may alsowish to periodically monitor their heart rate and blood pressure instressful situations, for example when engaging in strenuous exercise.

[0005] In order to support regular monitoring of human subjects in theirnormal environment, such as in the home and at the office for example,the equipment must be non-invasive and easy to use. The equipment wouldthen be able to monitor at least one physiological parameter of theuser, without requiring the user to perform any complicated actionsand/or to operate complex devices. Indeed, it would be highly preferredfor the equipment to be incorporated as part of the regular daily livingroutine of the subject, since the requirement for any additional orspecial actions on the part of human subject is likely to result indecreased compliance. In addition, the equipment should be robust yetinexpensive.

[0006] One example of such a device incorporates a wristband to attach aphysiological sensor to the wrist of the subject. Currently, a number ofdifferent types of such wristband devices are available, most of whichare intended to be used as stand-alone devices to provide informationabout the subject's own physical condition, mainly for heart rate andblood pressure. Most of these devices obtain such measurements by usingan inflating cuff, which is bulky and awkward for the subject.

[0007] Wrist-mounted heart rate monitors are known to the art and havebeen disclosed, for example, in the patent to Orr et al, U.S. Pat. No.3,807,388, wherein the duration of a heart beat is measured by countingelectrical pulses recurring at a known frequency. The duration of theheartbeat is then related to a particular average heart beat rate.However, the disclosed measurement system does not directly measure theheart rate and, therefore, is subject to inaccuracies of measurement dueto the instability of heart beat duration over brief intervals of time.

[0008] A blood pressure measuring device is disclosed in the patent toPetzke et al, U.S. Pat. No. 3,926,179, in which a probe is appliedadjacent to the radial artery of a wrist. A pressure-sensitivetransducer on the probe generates electrical signals corresponding tothe blood pressure pulses of the radial artery. The electrical pulsesare applied to analog circuitry that generates a systolic signalcorresponding to the integrated voltage at the peak of the electricalpulse signal and a diastolic signal corresponding to the voltage at thelow point of the pulse signal. The analog device of Petzke et alrequires a substantial amount of power to operate and, therefore, is notsuitable for use in a small, compact stand-alone device for being wornon the wrist.

[0009] A blood pressure and a heart rate measuring wrist watch is alsodisclosed in the patent to Broadwater, U.S. Pat. No. 4,331,154, in whicha digital watch is employed to measure systolic and diastolic bloodpressure as well as heart rate. The band of the watch supports apiezoelectric transducer that is held in contact with the wrist adjacentto the radial artery when a switch on the band is activated. Theabsolute values required for this method to evaluate blood pressurecause the device to be subject to inaccurate readings, since the tissuesof the hand and wrist may be expected to expand and contract accordingto such factors as the time of day, and the condition of the externalenvironment such as the atmospheric pressure. Such expansion orcontraction may cause different degrees of tension on the wrist-mounteddevice, which is therefore not suitable for use without dailycalibrations.

[0010] Other wrist-mounted devices are for wireless panic alarm systems,mainly for elderly people who live alone. These devices are usuallyshaped as a wristband or a pendant. Whenever the user becomesdistressed, the user presses a panic button located on the device. Thedevice then sends a digitally coded wireless message to a gateway devicelocated nearby, usually in the same room, by using a unidirectionalwireless data communication link. The gateway device then contacts amanually operated contact center, for example with a land based orcellular telephone connection. A particular identifier for the user isusually sent first, after which the human operator is allowed to talk tothe user through a speaker and to listen through a sensitive microphonelocated within the gateway. However, none of the above systems containsany physiological measurement device within, in order to learn about thecurrent physiological status of the user.

[0011] In such a situation as described above, the operator at the callcenter learns about the user's condition only by speaking with the user.However, this is only possible if the user is actually able to speak.High levels of background noise may also prevent the user from beingheard by the microphone of the gateway device.

SUMMARY OF THE INVENTION

[0012] The background art does not teach or suggest a device which canconveniently, non-intrusively and autonomously measure one or morephysiological parameters, in order to extract medical information suchas heart rate, breathing rate and blood pressure, and which may be wornon the wrist of the user. The background art also does not teach orsuggest such a wrist-mounted device which can measure such parametersand then send the information to a contact center or other locationcontaining medical personnel. The background art also does not teach orsuggest such a wrist-mounted device which is compact, non-invasive, andlight.

[0013] The present invention overcomes these deficiencies of thebackground art by providing a wrist-mounted device for measuring atleast one physiological parameter of the user. The present inventionenables such a measurement to preferably be transformed into medicalinformation about the user, and/or displays the results on a LCDdisplay. As used herein, the term “physiological parameter” refers tothe signal which is received from the sensor, while the term “medicalinformation” refers to the information which may be extracted orotherwise obtained by analyzing this signal and/or a combination ofsignals. Such information may then optionally be sent to medicalpersonnel (for example at a contact monitoring center) and/or to aremote server, through a gateway device. The gateway device preferablycommunicates with the wrist-mounted device of the present inventionthrough a wireless communication channel.

[0014] The present invention has the option to display the medicalinformation to the user on a local LCD display, such that the user isoptionally and preferably able to read the result locally.

[0015] Examples of medical information which may be extracted from themeasured physiological parameter or parameters include, but are notlimited to: heart rate; variability in heart rate; breathing rate;arrhythmia of the heart (if any), as well as the general rhythm andfunctioning of the heart; blood pressure; presence of abnormal bodymovements such as convulsions for example; body position; general bodymovements; body temperature; presence and level of sweat; oxygenpressure in the blood; and glucose levels in the blood.

[0016] Optionally and more preferably, the present invention alsofeatures an alarm signal for being transmitted through the gatewaydevice in order to indicate an emergency or otherwise dangeroussituation for the user. The alarm signal may optionally be transmittedaccording to a manual action of the user, such as pressing a “panicbutton” for example.

[0017] Upon receipt of the manually activated alarm signal, the gatewaywould preferably initiate immediately a call to a human operated callcenter. Then the device would preferably automatically collect one ormore current measurements of physiological parameters of the user. Thesemeasurements may be sent directly to the gateway, or alternatively maybe analyzed in order to compute the medical information of the userbefore sending the results to the gateway. The human operator would thenpreferably be able to assess the user's medical condition from thereceived information.

[0018] Most preferably, the alarm signal is transmitted automaticallyupon measurement of one or more physiological parameters of the user,preferably even if the user is unable to press the panic button.Optionally, the alarm signal may be given to the user, additionally oralternatively, for example by sounding an audible alarm, more preferablyfrom the wrist-mounted device itself.

[0019] The device of the present invention also monitors, at leastperiodically but more preferably continuously, one or more physiologicalparameters of the user. Continuous monitoring would more easily enablethe device to transmit the alarm signal if one or more physiologicalparameters are determined to be above predefined criteria, which mayrepresent such medical information as unstable or excessive heart rate,or very high or low blood pressure.

[0020] According to preferred embodiments of the present invention, thewrist-mounted device features one or more sensors attached to awristband or other fastening article. The sensor(s) are preferablyconnected to a microprocessor, optionally by a wire but alternativelythrough a wireless connection. The microprocessor may optionally also belocated within the wristband, or otherwise attached to the wristband.The sensor(s) preferably support automatic collection of the measurementof the at least one physiological parameter; more preferably, themicroprocessor is able to execute one or more instructions forextracting medical information about the user from such measurement(s).

[0021] The microprocessor more preferably operates a software program toprocess and analyze the data which is collected, in order to computemedical information. The extracted information, optionally also with theraw data, is then preferably transferred to the previously describedgateway device. The gateway device then preferably relays suchinformation to a remote server, which more preferably is able to providesuch information to medical personnel, for example as part of a contactcenter. Therefore, continuous monitoring of the medical informationand/or physiological parameters of the user may optionally and morepreferably be made, enabling better medical care for the user. Accordingto the present invention there is provided a device for measuring atleast one physiological parameter of a subject, comprising: (a) afastening article for being fastened to a wrist of the user; (b) asensor for measuring at least one physiological function of the user,the sensor being in contact with at least a portion of the wrist and thesensor being attached to the fastening article; and (c) a processor forreceiving a signal from the sensor and for converting at least onemeasurement to form the at least one physiological parameter. Optionallyand preferably, the data may be stored on a non-volatile memory forbeing downloaded later by the user or by an operator.

[0022] According to another embodiment of the present invention, thereis provided a system for measuring at least one physiological parameterof a subject, comprising: (a) a device for measuring the at least onephysiological parameter, comprising: (i) a fastening article for beingfastened to a wrist of the user; (ii) a sensor for measuring at leastone physiological parameter of the user, the sensor being in contactwith at least a portion of the wrist and the sensor being attached tothe fastening article; (iii) a communication unit for at leasttransmitting data; and (b) a gateway device for receiving thetransmitted data for being monitored.

[0023] According to another embodiment of the present invention, thereis provided a method for monitoring a physiological parameter of a user,comprising: providing a device for monitoring the physiologicalparameter, the device being attached to at least a portion of the userat a pulse point of the user; monitoring the physiological parameterthrough the pulse point; and if a level of the physiological parameterof the user is outside of an expected range, transmitting an alarm.

[0024] According to still another embodiment of the present invention,there is provided a device for measuring at least one physiologicalparameter of a subject, comprising: (a) a fastening article for beingfastened to a wrist of the user; (b) a piezoceramic sensor for measuringat least one physiological parameter of the user at a pulse point of thewrist and the sensor being attached to the fastening article; and (c) aprocessor for receiving a signal from the sensor and for converting theat least one measurement to form medical information.

[0025] Hereinafter, the term “microprocessor” includes, but is notlimited to, general-purpose microprocessor, a DSP, a micro-controller ora special ASIC designed for that purpose.

[0026] The method of the present invention could be described as aprocess for being performed by a data processor, and as such couldoptionally be implemented as software, hardware or firmware, or acombination thereof. For the present invention, a software applicationcould be written in substantially any suitable programming language,which could easily be selected by one of ordinary skill in the art. Theprogramming language chosen should be compatible with the computationaldevice (computer hardware and operating system) according to which thesoftware application is executed. Examples of suitable programminglanguages include, but are not limited to, Visual Basic, Assembler,Visual C, standard C, C++ and Java.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The invention is herein described, by way of example only, withreference to the accompanying drawings, wherein:

[0028]FIG. 1 is a schematic block diagram of a system according to thepresent invention;

[0029]FIG. 2 shows an exploded view of the device;

[0030]FIG. 3 describes a general state flow diagram; and

[0031]FIG. 4 describes a bi-directional message format between thedevice and the gateway.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] The present invention is of a wrist-mounted device for measuringat least one physiological parameter of the user. The present inventionenables such a measurement to preferably be transformed into medicalinformation about the user. Such information may then optionally be sentto medical personnel (for example at a contact monitoring center) and/orto a remote server, through a gateway device. The gateway devicepreferably communicates with the wrist-mounted device of the presentinvention through a wireless communication channel.

[0033] Examples of medical information which may be extracted from themeasured physiological parameter or parameters include, but are notlimited to: heart rate; variability in heart rate; breathing rate;arrhythmia of the heart (if any), as well as the general rhythm andfunctioning of the heart; blood pressure; presence of abnormal bodymovements such as convulsions for example; body position; general bodymovements; body temperature; presence and level of sweat; oxygenpressure in the blood; and glucose levels in the blood.

[0034] Optionally and more preferably, the present invention alsofeatures an alarm signal for being transmitted through the gatewaydevice in order to indicate an emergency or otherwise dangeroussituation for the user. The alarm signal may optionally be transmittedaccording to a manual action of the user, such as pressing a “panicbutton” for example.

[0035] Most preferably, the alarm signal is transmitted automaticallyupon measurement of the one or more physiological parameters of theuser, preferably even if the user is unable to press the panic button.Optionally, the alarm signal may be given to the user, additionally oralternatively, for example by sounding an audible alarm, more preferablyfrom the wrist-mounted device itself. Upon receipt of themanually/automatically activated alarm signal, the gateway wouldpreferably initiate immediately a call to a human operated call center.Then the device would preferably automatically collect one or morecurrent physiological measurements of the user. These measurements maybe sent directly to the gateway, or alternatively may be analyzed inorder to compute the medical parameters of the user before sending theresults to the gateway. The human operator would then preferably be ableto assess the user's medical condition from the received information.

[0036] The device of the present invention may also monitor, at leastperiodically but more preferably continuously, the value or condition ofone or more physiological parameters of the user. Continuous monitoringwould more easily enable the device to transmit the alarm signal ifmeasurements of one or more physiological parameters are collected andanalyzed by the microprocessor to form medical information, which thencould be determined to be above predefined criteria, such as unstableheart rate, or very high or low blood pressure, for example.

[0037] According to preferred embodiments of the present invention, thewrist-mounted device features one or more sensors attached to awristband or other fastening article. The sensor(s) are preferablyconnected to a microprocessor, optionally by a wire but alternativelythrough a wireless connection. The microprocessor may optionally also belocated within the wristband, or otherwise attached to the wristband.The sensor(s) preferably support automatic collection of at least onephysiological measurement; more preferably, the microprocessor is ableto execute one or more instructions for extracting clinically usefulinformation about the user from such measurement(s).

[0038] The microprocessor more preferably operates a software program toprocess and analyze the data which is collected, in order to computemedical information. The extracted medical information, optionally alsowith the raw data, is then preferably transferred to the previouslydescribed gateway device. The gateway device then preferably relays suchinformation to a remote server, which more preferably is able to providesuch information to medical personnel, for example as part of a contactcenter. Therefore, continuous monitoring of the physiological parametersof the user may optionally and more preferably be made, enabling bettermedical care for the user.

[0039] A general, non-limiting example of suitable formulae formeasuring the heart rate and/or other heart-related physiologicalparameters of a subject who is wearing the device according to thepresent invention may be found in the article “Cuff-less ContinuousMonitoring of Beat-To-Beat Blood Pressure Using Sensor Fusion”, byBoo-Ho Yang, Yi Zhang and H. Harry Asada—IEEE (also available throughhttp://web.mit.edu/zyi/www/pdf/IEEETrans2000.pdt as of Dec. 9, 2001),hereby incorporated by reference as if fully set forth herein, wheresystolic and diastolic blood pressure are calculated using the pulsepressure shape per heartbeat. The disclosure does not describe a devicewhich has the functionality according to the present invention, but thedisclosed method is generally useful for determining blood pressure froman external measurement of pressure from the pulse through the skin ofthe subject.

[0040] The principles and operation of a device and method according tothe present invention may be better understood with reference to thedrawings and the accompanying description.

[0041] Referring now to the drawings, FIG. 1 is a schematic blockdiagram of a system according to the present invention. As shown, asystem 1 features a wearable device 101 to be worn by a user, preferablyas a wrist-mounted device, for example by being attached with awristband or other fastening article to the wrist of the user. Device101 features at least one physiological sensor 102 for measuring atleast one physiological parameter of the user. The function of anexemplary sensor 102 is described in greater detail below.

[0042] The device 101 also preferably features a vibration sensor 123,preferably a piezoceramic sensor, which is not in direct contact withthe skin of the user. Sensor 123 measures the movement of the wrist. Theoutput of sensor 123 can be used by a processing unit 103 to capture themovement of the wrist and to recover some noise received by sensor 102which is caused by such movement.

[0043] In order to support processing of the measured physiologicalparameter or parameters, processing unit 103 more preferably includesinternal RAM and non-volatile program memory (not shown). Also morepreferably, processing unit 103 includes an extended data memory 105located externally to processing unit 103. Processing unit 103preferably executes at least one instruction for processing the dataobtained by sensor 102.

[0044] Examples of such processing units 103 include but are not limitedto PIC18LC452 by Microchip Technology Inc., which contains 10 channelsof 10 bit A/D converters, a 1.5K bytes of internal RAM and 32K Bytes ofnon-volatile program memory.

[0045] Extended memory component 105 is preferably an electricallyerasable non-volatile external memory component. Examples of such amemory component include but are not limited to FM24CL64-S (Ramtron,USA), with 64 Kbit of fast access read/write serial memory for storingtemporary data related to the sampled physiological parameter.

[0046] Device 101 optionally and preferably features a real time clock117 in order to provide an accurate time and date for each measurement,as device 101 can optionally store a few measurements beforetransmitting such data and/or information to a gateway device 110, asdescribed in greater detail below. Stored data and/or information mayalso optionally be used for such applications as reminding the subjectto take medication, perform a medical diagnostic measurement, and soforth. An A/D converter 109 with multiple inputs is also optionally andpreferably present if sensor 102 is an analog sensor, in order toconvert the analog signal to a digital signal.

[0047] Device 101 preferably features an internal communication unit104, for at least unidirectional, but more preferably bi-directional,communication with gateway device 110. Gateway device 110 alsopreferably features a communication unit 107. Communication unit 104 mayoptionally communicate with communication unit 107 through a wire oralternatively through a wireless communication link 121. According topreferred embodiments of the present invention, gateway device 110 islocated relatively close to the user and hence to device 101, forexample by being located in the same building. As a non-limitingexample, gateway device 110 could optionally be installed in the home ofthe user.

[0048] Gateway device 110 also optionally and preferably features acontroller 108 for controlling functions of gateway device 110, such ascommunication with device 101 for example.

[0049] Gateway device 110 preferably communicates with a remote server114 through a data link 120, which could optionally be a direct dial-upmodem connection with DTMF coding or TCP/IP using regular LAN or dial-upmodem connection to an ISP, for example. In any case, data link 120 mayoptionally be a wired or wireless link, for example through a cellulartelephone and/or land-based telephone system, or a combination thereof.

[0050] Remote server 114 optionally and more preferably features asystem administrator 112, which may be a person (for manual operation)or a software program (for automatic operation), or a combinationthereof. Remote server 114 also preferably features a database 113 forstoring data received from gateway device 110.

[0051] Device 101 may also feature a manually operated panic alarmbutton 116 to be manually activated by the user, for example if the useris in distress. Device 101 may also optionally feature a LED display118, for example in order to indicate of alert activation or a lowbattery level.

[0052] Physiological sensor 102 is preferably part of a sensor assembly.Without wishing to be limited in any way, the following discussioncenters around such a physiological sensor 102 which contains apiezoceramic transducer for generating an electrical signal, having anamplitude corresponding to the magnitude of applied pressure. Therefore,if at least a portion of the transducer is located adjacent to, and inphysical contact with, an area of the wrist where blood pressure pulsesmay be detected, the transducer generates electrical pressure pulsescorresponding to the detected blood pressure pulses. Each of theelectrical pressure pulses preferably defines a maximum voltage over asystolic interval and a minimum voltage over a diastolic interval.

[0053] Although a piezoceramic sensor is used as a pressure transduceraccording to a preferred embodiment of the invention, it should beappreciated that other transducers known to the art may be employedwithout departing from the spirit of the invention. Examples of suchsensors include but are not limited to piezoelectric transducers,resistive strain gauges and pressure sensor made of fiber-optictechniques.

[0054] The piezoceramic transducer is desirable for the presentinvention since the transducer measures the direct effect of thepressure exerted within the radial artery, while other transducers, forexample resistive strain gauges, measure secondary effects such as thestrain forces that are applied at the surface of the skin due to theexpansion of the radial artery. Piezoceramic transducers are alsocheaper than piezoelectric transducers but still produce a high-qualitysignal.

[0055] As shown with regard to FIG. 1, the analog output of sensor 102is first preferably treated by an analog front-end 119 which morepreferably contains an analog filter (not shown). As a non-limitingexample, this analog filter preferably has a cutoff of about 20Hz, alinear phase response, a flat amplitude response up to 10 Hz and anamplification of about 3 for acquiring the full spectrum of a typicalblood pressure pulse. The filtered signal then enters A/D converter 109.

[0056] Processing unit 103 preferably controls the operation of A/Dconverter 109. When a physiological measurement is initiated, A/Dconverter 109 starts sampling the filtered analog signal of sensor 102from analog front-end 119, preferably at a rate controlled by processingunit 103. This rate is optionally and more preferably 80 samples persecond as to over sample the data by a factor of 4 to maintain a goodquality sampled signal. A/D converter 109 preferably transfers theanalog data into a digital coded word, preferably at resolution of 10bits per sample.

[0057] Preferably about 30 seconds of data is gathered for eachmeasurement. Processing unit 103 preferably operates a software programfor examining the validity of the sampled data, in order to determinewhether the data contains some indications of legitimate physiologicaldata (such as of a blood pressure pulse of an artery) or alternativelywhether the data contains only noise or poor readings. In the secondcase, A/D converter 109 preferably starts sampling the signal again inorder to obtain data for measurement. This process preferably continuesuntil the software determines that sufficient valid data has beencollected or after a few successive rejections (usually after 3 times).

[0058] Then, the software program preferably performs an algorithm forcalculating some medical parameters from the sampled data, such as thecalculation of systolic and diastolic blood pressure using a method asdisclosed in the previously described U.S. Pat. No. 4,418,700, which ishereby incorporated by reference as if fully set forth herein.

[0059] The calculated parameters are then preferably stored in memory105. The data stored in memory 105 is preferably transmitted to gatewaydevice 110 periodically, or alternatively or additionally after manualoperation of panic button 116.

[0060] The calculated parameters are also optionally and preferablydisplayed on a local LCD display (124), so the user can view the lastmedical results locally.

[0061] More preferably, data for all medical parameters that are sent toremote server (114) are sent according to a security protocol formaintaining the privacy of the user.

[0062] Furthermore, the software program preferably performs anotheralgorithm for generating an alert if the medical parameters have valuesbeyond or otherwise outside of the normal expected values.

[0063] Although a one-way link from device 101 to gateway device 110 maybe used, device 101 preferably features a two-way communication link asshown for link 121, for establishing more reliable communication withgateway device 110. Examples of communication units 104, 107 include butare not limited to a nRF401 UHF transceiver (Nordic), which operates inthe universal ISM band (433.92 Mhz), an infrared transceiver, and a“Bluetooth” protocol enabled-transceiver operating bi-directionally inthe 2.4 GHz band.

[0064] Device 101 preferably has its own unique identifier, stored innon-volatile data storage, more preferably in memory 105. Each timedevice 101 sends a wireless message to gateway device 110, device 101also preferably sends the unique identifier to gateway device 110,although optionally the identifier may be sent only periodically, forexample once per day. Gateway device 110 also preferably sends a messageto a particular device 101 by including the device identifier in themessage, thereby specifying which such device should receive themessage.

[0065] As previously described, device 101 preferably has its own realtime clock 117. For periodic monitoring of the user, real time clock 117is preferably used to provide a time tag for each set of results. Thistime tag is very important for continuous monitoring of the user forlong periods of time. By examining the data recorded over of the userfor long period of time, a change or alteration in the health conditionof the user may be detected. Real time clock 117 may optionally beimplemented by separate hardware such as RTC8564 (EPSON, US) forexample, or alternatively by a software program for operation byprocessing unit 103.

[0066] Device 101 also preferably features a power source such as abattery 106, which powers device 101. Examples of suitable batteriesinclude but are not limited to the silver oxide coin battery model 386(Panasonic, Japan) having 150 mAh in capacity with a pulse burst of 75mA for a short period of time (about 5 sec for each pulse). Battery 106optionally and preferably contains enough energy to power the device formore than one year of operation without being replaced.

[0067]FIG. 2 shows an exploded view of the exemplary device according toFIG. 1. As shown, the device features sensor 102, shown with thepreferred but exemplary implementation of a piezoceramic sensor aspreviously described. The device also optionally and preferably featuresbattery 106, and a push button 316 (for optional implementation of thealarm button of the device of FIG. 1). Battery 106 may optionally bereplaced with a plurality of smaller batteries (not shown). The devicepreferably features a processor 314 (which may optionally be similar oridentical to the processing unit of the device of FIG. 1).

[0068] For this exemplary implementation, sensor 102 is in physicalcontact with an anvil 300. Anvil 300 preferably features a protrusion302 which presses against the skin of the wrist of the subject (notshown), more preferably at a pulse point. Protrusion 302 thereforereceives pressure with each pulse of the blood of the subject. Thispressure is transduced through anvil 300 to sensor 102, which then emitsvoltage to form a signal, preferably according to a linear output.

[0069] This signal is then received by processor 314, which preferablyextracts medical information from the measurement of the physiologicalparameter. Processor 314 optionally and preferably features a crystaloscillator 314, for stabilizing the internal clock of processor 314.Processor 314 is also preferably in contact with the real time clock ofthe device (not shown). Also not shown are the extended memory,transceiver (communication unit), A/D converter and analog front end ofthe device.

[0070] Processor 314, oscillator 312 and push button 316 are allpreferably mounted on a PCB board 308. PCB board 308 is then preferablysandwiched between battery 106 and a device cover 304. Device cover 304preferably features a soft cover, which may be rubber for example, forenabling the user to locate and depress the alarm button through pushbutton 316.

[0071] An o-ring 310 is preferably used for waterproof sealing betweenthe upper and the bottom parts of the device. Anvil 300 then is heldbetween sensor 102 and the skin of the user (not shown), for example bybeing affixed to sensor 102 with an adhesive substance.

[0072] According to an alternative implementation of the device of FIGS.1 and 2, sensor 102 and anvil 300 could optionally be located in thewristband for affixing the device to the wrist of the user (not shown).

[0073]FIG. 3 is a flow chart of the operation of the device. As thedevice software begins operation for the first time, the softwarepreferably makes some initializations using default values. Once thedevice has been initialized, the software preferably triggers a watchdogfunction shown as a “Watchdog” process, and then enters a sleeping modefor saving battery life, shown as a “Sleep” process.

[0074] If the end of a watchdog time period is reached, the device isassumed to have a fault in its operation, and a master reset ispreferably initiated automatically.

[0075] The device is preferably “woken up” according to one of threetriggers. First, the device is preferably woken up when the user pressesa panic button manually. This process is shown by the “Alarm” state. Thedevice then preferably immediately starts a transmission to the gatewaydevice, containing a distress indication and the device identifier. Thenthe device enters a receiving mode for a few seconds, waiting foracknowledge (ACK) from the gateway device. This process is shown as a“TX/RX” state.

[0076] If the acknowledge message is not received within this period oftime a repeated message is initiated. Additional transmissions areinitiated, if necessary. However, if after a predefined number ofrepeated times an acknowledge message is not received, an error messageis stored within a log and no more tries are made. More preferably anindication LED starts blinking for a few seconds, optionally with anaudible alarm. Then, the process returns to the “Sleep” state.

[0077] After receiving acknowledge, the process turns to “Supervise”state, where the device collects data from its sensors, preferablycalculates some medical information concerning the current physiologicalstatus of the user. Then, it turns into “Tx/Rx” state, where the devicetransmits a message containing the identifier, and the calculatedmedical parameters. And if the received ACK contains no commands itreturns to the “Sleep” state, otherwise it does the command and sends anACK to the gateway. The gateway returns an ACK with another command tocontinue or without a command to terminate this process. After doing thelast command the device returns to the “Sleep” state.

[0078] In the next case where the device exits its “Sleep” state, anexternal real time clock signals the device to execute an automaticcheck. Then, the process enters “Supervise” state as discussed in theabove paragraph, only that this time for saving battery life, the deviceinitiate the “Tx/Rx” process only once for a few successive timessending all the accumulated data in one transmission. Then, the devicepreferably enters a “Sleep” state unless the measured parameters exceeda predefined threshold at least once, but preferably for a fewsuccessive measurements. In this case, the device initiates an automaticalarm entering the “Alarm” state, if the device has permission to do so,as previously described.

[0079] When a timer for a supervise process has been running or after analarm, the device preferably exercises an automatic check as describedabove, and after that initiates a transmission to the gateway deviceincluding all the data collected after the last transmission. Then thedevice preferably waits for acknowledge, preferably repeating thetransmission again if not receiving such an acknowledge message. In theacknowledge message, a command for the device can be stored. In such acase the device performs this command and then it sends an acknowledgemessage to the gateway device. This process may optionally continueuntil an acknowledge message without a command is received, after whichthe device preferably returns to sleep mode.

[0080] In the third case, the device exit “Sleep” mode if of technicalreasons a technician wants to change the operation software, the deviceenters “Boot Loader” state where a new software is loaded “on the fly”without a need to disconnect the batteries.

[0081]FIG. 4 describes an exemplary message format for exchangingmessages between the device and the gateway device. Every messagepreferably starts with a preamble STX byte (hex 7E), followed by a bytewhich contains the number of bytes in the current message, and threebytes of address, followed by a command byte and its corresponding databytes. This is followed by two bytes of CRC and an ETX byte (hex 7B).

[0082] As such, the message is a variable length message with strongerror detection and correction method for enhanced communicationreliability. Each message optionally and preferably contains a lowbattery indication, if necessary.

[0083] In case of a unidirectional communication link between the deviceand the gateway, a repeated message is preferably transmitted for apredefined number of times, such as 20 times for example, after whichthe device preferably enters a sleeping mode if no answer is received.

[0084] In case of a bi-directional link, for each message sent to thegateway device, an acknowledge message is preferably returned by thegateway device and vise versa. This message may also contain a commandfor the device encoded in the CMD byte within the message. Commandscould optionally include, but are not limited to, one or more of thefollowing:

[0085] 1) Get/Set service type

[0086] 2) Get/Set device ID

[0087] 3) Set interval between successive medical checking

[0088] 4) Set interval between successive supervision transmissions

[0089] 5) Set Time and date

[0090] 6) Set threshold for automatic alerts

[0091] 7) Set device calibration

[0092] Each time the device sends a message to the gateway, it mayoptionally contain a Battery OK/Battery Low indication for the batterysituation. This signal preferably appears three months before thebattery finishes, enough time to ask the user to replace the battery.

[0093] Each time the device sends a supervise-type message to thegateway, it preferably sends also all the medical data stored in itsmemory with that message.

[0094] Each time the gateway device sends a command back to the device,the device preferably returns an acknowledge message with a 3 bitmessage serial number to the gateway device, in order to fulfill a fullhandshake between the two. If the gateway device does not receiveacknowledge from the device within a few seconds, the gateway devicepreferably sends its transmission message again with the same serialnumber. The message may even be repeated a few times, each time waitingfor acknowledge. If acknowledge is not received, a logbook is updatedwith an error message, and more preferably an indication LED is turnedon for error indication.

[0095] It will be appreciated that the above descriptions are intendedonly to serve as examples, and that many other embodiments are possiblewithin the spirit and the scope of the present invention.

What is claimed is:
 1. A device for measuring at least one physiologicalparameter of a subject, comprising: (a) a fastening article for beingfastened to a wrist of the user; (b) a sensor for measuring at least onephysiological parameter of the user, said sensor being in contact withat least a portion of said wrist and said sensor being attached to saidfastening article; and (c) a processor for receiving a signal from saidsensor and for converting said at least one measurement to form medicalinformation.
 2. The device of claim 1, wherein said sensor is an analogsensor, the device further comprising an A/D (analog to digital)converter for receiving an analog signal from said sensor and forconverting said analog signal to a digital signal, said digital signalbeing sent to said processor.
 3. The device of claim 2, wherein a rateof sampling by said A/D converter is determined by said processor. 4.The device of claim 3, wherein said rate of sampling is at leastpartially determined according to a type of physiological parameterbeing measured.
 5. The device of claim 1, wherein said physiologicalparameter is heart-related.
 6. The device of claim 5, wherein saidphysiological parameter includes at least one of heart rate and bloodpressure.
 7. The device of claim 6, wherein said sensor is selected fromthe group consisting of a piezoceramic transducer, a piezoelectrictransducer, a resistive strain gauge and a pressure sensor withfiber-optic components.
 8. The device of claim 5, wherein saidphysiological parameter includes variability in heart rate.
 9. Thedevice of claim 5, wherein said physiological parameter includesbreathing rate.
 10. The device of claim 5, wherein said physiologicalparameter includes at least one of arrhythmia and overall cardiacrhythm.
 11. The device of claim 5, wherein said physiological parameterincludes body movements.
 12. The device of claim 11, wherein said bodymovements include presence of abnormal body movements.
 13. The device ofclaim 5, wherein said physiological parameter includes body temperature.14. The device of claim 1, further comprising: (d) a non-volatile memoryfor storing at least one instruction for execution by said processor.15. The device of claim 1, further comprising: (e) a communication unitfor at least transmitting data.
 16. The device of claim 15, wherein saidcommunication unit also transmits a device identifier for uniquelyidentifying the device.
 17. The device of claim 15, wherein saidcommunication unit also receives data.
 18. The device of claim 1,wherein said fastening article is a wristband.
 19. A system formeasuring at least one physiological parameter of a subject, comprising:(a) a device for measuring the at least one physiological parameter,comprising: (i) a fastening article for being fastened to a wrist of theuser; (ii) a sensor for measuring at least one physiological parameterof the user, said sensor being in contact with at least a portion ofsaid wrist and said sensor being attached to said fastening article;(iii) a communication unit for at least transmitting data; and (b) agateway device for receiving said transmitted data for being monitored.20. The system of claim 19, wherein said transmitted data is monitoredmanually.
 21. The system of claim 20, further comprising: (c) a remoteserver in communication with said gateway device, said remote serverproviding said transmitted data to a human operator for manualmonitoring.
 22. The system of claim 21, wherein at least one of acommunication link between said gateway device and said remote serverincludes a telephonic connection.
 23. The system of claim 19, whereinsaid transmitted data is monitored at least partially automatically bysaid gateway device.
 24. The system of claim 19, wherein said device andsaid gateway device communicate bi-directionally, such that a messagetransmitted from said device is acknowledged by said gateway device, andsuch that if said gateway device does not acknowledge correct receptionof said message, said device transmits said message again.
 25. Thesystem of claim 19, wherein said device for measuring the at least onephysiological parameter further comprises: (iv) a processor forreceiving a signal from said sensor and for converting at least onemeasurement to form medical information.
 26. The system of claim 19,wherein at least one of a communication link between said device andsaid gateway device is a wireless link.
 27. The system of claim 19,wherein at least one of a communication link between said device andsaid gateway device is a wired link.
 28. The system of claim 19, whereinsaid communication unit of said device also receives data, such thatcommunication between said device and said gateway device includes anacknowledge procedure.
 29. The system of claim 19, wherein said deviceautomatically performs a measurement of the physiological parameter uponmanual activation of an alarm function by the subject.
 30. The system ofclaim 29, wherein said data is automatically transmitted to said gatewaydevice upon said manual activation.
 31. The system of claim 19, whereinsaid device automatically and periodically performs a measurement of thephysiological parameter.
 32. The system of claim 31, wherein said datais automatically transmitted to said gateway device if said measurementis outside of an acceptable range.
 33. The system of claim 32, whereinsaid measurement is combined with another measurement of at least oneother parameter to determine if said measurements are outside of saidacceptable range.
 34. A method for monitoring a physiological parameterof a user, comprising: providing a device for monitoring thephysiological parameter, said device being attached to at least aportion of the user at a pulse point of the user; monitoring thephysiological parameter through said pulse point; and if a level of thephysiological parameter of the user is outside of an expected range,transmitting an alarm.
 35. A device for measuring at least onephysiological parameter of a subject, comprising: (a) a fasteningarticle for being fastened to a wrist of the user; (b) a piezoceramicsensor for measuring at least one physiological parameter of the user ata pulse point of said wrist and said sensor being attached to saidfastening article; and (c) a processor for receiving a signal from saidsensor and for converting said at least one measurement to form medicalinformation.